T-Flip-Flop in Minecraft

The first thing we need is a repeater on the third delay-level (two-right-clicks). Install a redstone-lane around the repeater.

Put a block with a redstone-torch on its side in front of the repeater.
t-flip_flop-2

Put a button on it‘s front.
t-flip_flop-3

Add another repeater.

Add another repeater, which should enter the „locked mode“ automatically.

Build a block behind this repeater with a redstone-torch on it‘s side and connect the signal of this torch with the repeater. This is also the output-lane. Use the button as an input.